CN104867442A - Pixel circuit and display device - Google Patents

Pixel circuit and display device Download PDF

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Publication number
CN104867442A
CN104867442A CN201410058991.9A CN201410058991A CN104867442A CN 104867442 A CN104867442 A CN 104867442A CN 201410058991 A CN201410058991 A CN 201410058991A CN 104867442 A CN104867442 A CN 104867442A
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transistor
pole
circuit
light
coupled
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CN201410058991.9A
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CN104867442B (en
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张盛东
王翠翠
冷传利
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北京大学深圳研究生院
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Abstract

The application discloses a pixel circuit and a display device. The pixel circuit comprises a storage capacitor, a third transistor, a second transistor and a light-emitting branch used for connecting in series between a first common electrode and a second common electrode, and the light-emitting branch comprises a fifth transistor, a driving transistor, a sixth transistor and a light-emitting element which are connected in series. In an initialization stage, the third transistor and the fifth transistor conduct and initialize the potentials at the two ends of the storage capacitor, in a programming stage, the second transistor inputs a data signal to one end of the storage capacitor via the third transistor and stores, and in an luminescence stage, the driving transistor drives the light-emitting element to emit light according to the voltage difference at the two ends of the storage capacitor. By the pixel circuit and the display device, the threshold voltage of the driving transistor and the degeneration of the light-emitting element can be compensated, at the same time, the contrast of a display also can be increased.

Description

A kind of image element circuit and display device

Technical field

The application relates to a kind of display device, particularly relates to a kind of image element circuit and display device.

Background technology

Organic Light Emitting Diode (Organic Light-Emitting Diode, OLED) display, because having the advantages such as high brightness, high-luminous-efficiency, wide viewing angle and low-power consumption, is extensively studied by people in recent years, and is applied to rapidly in the middle of display of new generation.The type of drive of OLED display can be passive waked-up (Passive MatrixOLED, PMOLED) and driven with active matrix (Active Matrix OLED, AMOLED) two kinds.Although passive waked-up is with low cost, there is cross-talk phenomenon and can not realize high-resolution display, and passive waked-up electric current is large, reduces the serviceable life of OLED.By contrast, driven with active matrix mode arranges the different transistor of number on each pixel as current source, avoid cross-talk, required drive current is less, power consumption is lower, the life-span of OLED is increased, can realize high-resolution display, meanwhile, driven with active matrix more easily meets the needs of large area and high grade grey level display.

The image element circuit of tradition AMOLED is simple two Thin Film Transistor (TFT) (Thin FilmTransistor, TFT) structure, generally includes multiple controlling grid scan line, multiple data line, multiple power lead and is connected to these lines and the multiple pixels arranged in the matrix form.OLED is current mode luminescent device, and its brightness is directly proportional to the electric current passed through.In traditional AMOLED pixel circuit, as shown in Figure 1, the electric current flowing through OLED can change along with the time thus cause the problem of non-uniform of display, and this is because the threshold voltage of driving transistors T1 and the voltage at OLED two ends can change along with the time, thus causes the change of electric current.Although this circuit structure is simple, can not compensation for drive transistor T1 threshold voltage shift, OLED threshold voltage shift or the panel problems such as transistor threshold voltage is uneven everywhere.

In addition, because this image element circuit is in the non-luminescent stage, still there is electric current to flow through OLED, thus reduce the contrast of image element circuit.

At present, in order to the problem that the threshold voltage shift solving transistor brings, the technique adopted regardless of the image element circuit of AMOLED is polysilicon (poly-Si) technology, amorphous silicon (a-Si) technology or oxide semiconductor technology, and it all needs when forming image element circuit to provide threshold voltage compensation mechanism.The current image element circuit having occurred much affording redress, these circuit roughly can be divided into two classes: current drive-type image element circuit and voltage driven type image element circuit.

Current drive-type image element circuit mainly adopts current mirror or current source data current to be copied as by a certain percentage the mode of drive current to light illuminating part.Because OLED is current mode device, therefore employing current drive-type circuit can the very accurate drift of compensating threshold voltage and the difference of mobility.But when practical application, due to the parasitic capacitance effect on data line, the foundation of data current needs the longer time, and this problem is more outstanding when small area analysis, has had a strong impact on the actuating speed of circuit.In addition, along with the size of display increases, stray capacitance and resistance increasing, when data current is less, discharge and recharge retardation ratio is comparatively large, and therefore current mode image element circuit is not suitable for manufacturing large area, high-resolution display.

Voltage driven type image element circuit has very fast charge/discharge rates relative to current drive-type image element circuit, can meet the needs of large area, high-resolution display.But voltage-type image element circuit can not the drift of very accurate compensating threshold voltage, and has been difficult to compensating action for the difference of different components mobility on panel.In addition, structure can be made in the process that voltage-type image element circuit changes at compensating threshold voltage to become complicated, reduce aperture opening ratio, and the more complicated that many drive singal make peripheral drive circuit become can be introduced.

Summary of the invention

The application provides a kind of image element circuit and display device, thus the threshold voltage shift of compensation transistor.

According to the first aspect of the application, the application provides a kind of image element circuit, comprising:

Memory capacitance, third transistor, transistor seconds and for being coupling in the luminous branch road between the first public electrode and the second public electrode.

Luminous branch road comprises the 5th transistor, driving transistors, the 6th transistor and the light-emitting component of series connection; Wherein, the 5th strings of transistors is associated between the first public electrode and driving transistors, and the 6th strings of transistors is associated between the second public electrode and driving transistors; The control pole of the 5th transistor is for inputting the first control signal; The control pole of the 6th transistor is for inputting the second control signal; First pole of driving transistors is coupled to the second pole of the 5th transistor, and the second pole is coupled to the first pole of the 6th transistor, controls pole and is coupled to Section Point.

The control pole of third transistor is for inputting sweep signal, and the first pole and the second pole are coupled respectively to the first pole and the Section Point of driving transistors.

The control pole of transistor seconds is for inputting sweep signal, and the first pole is coupled to the second pole of driving transistors, and the second pole is used for input data signal.

The first end of memory capacitance is coupled to Section Point, and the second end is coupled to the second pole of the 6th transistor.

In programming phases, 5th transistor and the 6th transistor respond the first control signal and the second control signal respectively and disconnect, and the threshold voltage of data-signal and driving transistors is stored in Section Point by transistor seconds and third transistor responding scanning signal conduction.

In glow phase, transistor seconds and third transistor respond input sweep signal respectively and disconnect, 5th transistor and the 6th transistor respond the first control signal and the second control signal and conducting respectively, and driving transistors conducting under the control of Electric potentials of Section Point provides drive current for light-emitting component.

According to the second aspect of the application, the application provides a kind of display device, comprising:

Image element circuit matrix, image element circuit matrix comprises the above-mentioned image element circuit being arranged in n capable m column matrix, n and m be greater than 0 integer.

Gate driver circuit, for generation of scanning pulse signal, and provides sweep signal by each horizontal scanning line formed along first direction to image element circuit.

Data drive circuit, for generation of the data voltage signal representing half-tone information, and provides data voltage signal by each data line formed along second direction to image element circuit.

Controller, for providing Control timing sequence to gate driver circuit and data drive circuit.

According to the third aspect of the application, the application provides a kind of driving method of above-mentioned image element circuit, and each drive cycle of image element circuit comprises initial phase, programming phases and glow phase, and driving method comprises:

At initial phase, the current potential at third transistor and the 5th transistor turns initialization memory capacitance two ends;

In programming phases, third transistor and transistor seconds conducting, the threshold voltage of data-signal and driving transistors inputs to the first end of memory capacitance by transistor seconds and third transistor, and is stored in this end by memory capacitance;

In glow phase, driving transistors produces drive current according to the pressure differential at memory capacitance two ends, and drives light-emitting component luminous.

The beneficial effect of the application is: the image element circuit adopting the application, by connecing the 3rd switching transistor between the control pole and the first pole of driving transistors, utilize this circuit structure and coordinate the switching transistor of luminous branch road, at the threshold voltage of programming phases storing driver transistor, thus the problem of threshold voltage variation in glow phase compensation for drive transistor, to reduce the problem of non-uniform of display.

Accompanying drawing explanation

Fig. 1 is the uncompensated image element circuit structure figure of prior art;

Fig. 2 is the circuit structure diagram of the embodiment of the present application one;

Fig. 3 is the signal timing diagram of the embodiment of the present application one;

Fig. 4 is the circuit structure diagram of the embodiment of the present application two;

Fig. 5 is the signal timing diagram of the embodiment of the present application two;

Fig. 6 is the circuit structure diagram of the embodiment of the present application three;

Fig. 7 is the embodiment of the present application four display device structure figure.

Embodiment

By reference to the accompanying drawings the present invention is described in further detail below by embodiment.

First some terms are described: the transistor in the application can be the transistor of any structure, such as bipolar transistor (BJT) or field effect transistor (FET).When transistor is bipolar transistor, it controls pole and refers to the base stage of bipolar transistor, and first can be extremely collector or the emitter of bipolar transistor, and second of correspondence can be extremely emitter or the collector of bipolar transistor; When transistor is field effect transistor, it controls pole and refers to the grid of field effect transistor, and first can be extremely drain electrode or the source electrode of field effect transistor, and second of correspondence can be extremely source electrode or the drain electrode of field effect transistor.Transistor in display is generally a kind of field effect transistor: thin film transistor (TFT) (TFT).Be field effect transistor below with transistor for example is described in detail the application, transistor also can be bipolar transistor in other embodiments.

Light-emitting component is Organic Light Emitting Diode (Organic Light-Emitting Diode, OLED), in other embodiments, also can be other light-emitting component.

It should be noted that: the first public electrode VDD and the second public electrode VSS is not a part for the application's image element circuit, in order to the technical scheme making those of ordinary skill in the art understand the application better, and introduce the first public electrode VDD especially and the second public electrode VSS is described.

Embodiment one:

Please refer to Fig. 2, Figure 2 shows that the structure of a kind of embodiment of the application's image element circuit, comprising: memory capacitance CS, third transistor T3, transistor seconds T2 and for being coupling in the luminous branch road between the first public electrode VDD and the second public electrode VSS.Luminous branch road comprises the 5th transistor T5, driving transistors T1, the 6th transistor T6 and light-emitting component OLED of series connection.

Wherein, 5th transistor T5 is connected between the first public electrode VDD and driving transistors T1,6th transistor T6 is connected between the second public electrode VSS and driving transistors T1, and the control pole (such as grid) of the 5th transistor T5 is for inputting the first control signal EM; The control pole (such as grid) of the 6th transistor T6 is for inputting the second control signal EN; First pole (such as draining) of driving transistors T1 is coupled to second pole (such as source electrode) of the 5th transistor T5, second pole (such as source electrode) is coupled to first pole (such as draining) of the 6th transistor T6, controls pole (such as grid) and is coupled to Section Point B.

In one embodiment, light-emitting component OLED can be connected between the first public electrode VDD and the 5th transistor T5, also can be connected between the second public electrode VSS and the 6th transistor T6.In the present embodiment, the first end of light-emitting component OLED is coupled to second pole (such as source electrode) of the 6th transistor T6, and the second end is coupled to the second public electrode VSS.

The control pole (such as grid) of third transistor T3 is for inputting sweep signal VSCAN, and the first pole (such as draining) and the second pole (such as source electrode) are coupled respectively to the first pole (such as draining) and the Section Point (B) of driving transistors T1.

The control pole (such as grid) of transistor seconds T2 is for inputting sweep signal VSCAN, and the first pole is coupled to second pole (such as source electrode) of driving transistors T1, and the second pole (such as source electrode) is for input data signal VDATA.

The first end of memory capacitance CS is coupled to Section Point B, and the second end is coupled to second pole (such as source electrode) of the 6th transistor T6.

In the present embodiment, be for all crystals pipe the course of work that N channel transistor sets forth the present embodiment.Image element circuit drives process to be divided into initial phase, programming phases and glow phase, is illustrated in figure 3 the signal sequence of the present embodiment, specifically describes the driving process of the present embodiment below in conjunction with Fig. 2 and Fig. 3.

At initial phase, the first control signal EM is high level, and the second control signal EN is low level, and sweep signal VSCAN is high level, and therefore, the 6th transistor T6 disconnects, and transistor seconds T2, third transistor T3 and the 5th transistor T5 all open.In this stage, the Coupling point of the 3rd node C(the 6th transistor T6 and memory capacitance CS second end) be coupled to the second public electrode VSS, therefore, the current potential of the 3rd node C is close to the current potential of the second public electrode VSS, after this stage, the initial potential of note the 3rd node C is V c; Section Point B is coupled to the first public electrode VDD by the third transistor T3 of conducting and the 5th transistor T5, and therefore, the current potential of Section Point B is close to the current potential of the first public electrode VDD, and conducting driving transistors T1.

In programming phases, the first control signal EM is low level, and the second control signal EN is low level, and sweep signal VSCAN is high level, and therefore, the 5th transistor T5 disconnects, transistor seconds T2 and third transistor T3 still conducting.In this stage, on the one hand, the current potential of the 3rd node C remains unchanged; On the other hand, third transistor T3 and driving transistors T1 constitutes the connection of diode form.So Section Point B starts electric discharge, until driving transistors T1 disconnects.When driving transistors T1 disconnects, the current potential of Section Point B is discharged to be stablized to V dATA+ V tH1, wherein, V dATAfor the voltage of the data-signal VDATA that transistor seconds T2 second pole (such as source electrode) inputs, V tH1for the threshold voltage of driving transistors T1.Therefore, at the end of this stage, the voltage difference of memory capacitance CS two ends (Section Point B and the 3rd node C) is V dATA+ V tH1-V c.Memory capacitance CS stores this voltage difference.

In glow phase, the first control signal EM is high level, and the second control signal EN is high level, and sweep signal VSCAN is low level, therefore, and the 5th transistor T5 and the 6th transistor T6 conducting; Transistor seconds T2 and third transistor T3 disconnects.Now, because Section Point B is in suspended state, therefore, the voltage difference at memory capacitance CS two ends keeps V dATA+ V tH1-V cconstant, the drive current flowing through light-emitting component OLED is:

I OLED = β 2 ( V DATA + V TH 1 + V OLED - V C - V DS 6 - V OLED - V TH 1 ) 2 - - - ( 1 )

Wherein, V tH1for the threshold voltage of driving transistors T1; V oLEDfor the voltage drop at OLED two ends; V dS6be first pole, pole-the second (such as drain-source) voltage of the 6th transistor T6, have nothing to do with the threshold voltage of driving transistors T1 and the voltage at light-emitting component OLED two ends, α I can be expressed as oLED.So formula can be reduced to:

I OLED = β 2 ( V DATA - V C - V DS 6 ) 2 = β 2 ( V DATA - V C - α I OLED ) 2 - - - ( 2 )

Wherein, β is gain factor, β=μ C oX(W/L) μ and C oXbe respectively the carrier mobility of driving transistors and the unit-area capacitance of gate insulation layer, W and L represents channel width and the length of driving transistors respectively, and α is and V tH1and V oLEDirrelevant coefficient.As can be seen from the above equation, the drive current I of light-emitting component OLED is flow through oLEDonly with the voltage V of current data signal VDATA dATAand the 3rd initial potential V of node C crelevant, with the threshold voltage V of driving transistors T1 tH1and the voltage V at light-emitting component OLED two ends oLEDirrelevant, thus compensate for the change of driving transistors T1 threshold voltage and the brightness irregularities problem of light-emitting component OLED degeneration generation in time.

Further, image element circuit can also comprise the 4th transistor T4.First pole (such as draining) of the 4th transistor T4 is coupled to the first end of light-emitting component OLED, and the second pole (such as source electrode) is for input reference voltage V rEF, control pole (such as grid) for inputting sweep signal VSCAN; When light-emitting component OLED is in non-luminescent state, the 4th transistor T4 conducting, is in luminance at light-emitting component OLED, and the 4th transistor T4 disconnects.Be specially: at initial phase, the high level conducting of the 4th transistor T4 responding scanning signal VSCAN, with reference to voltage V rEFinput the 3rd node C, now, the initial potential V of the 3rd node C c=V rEF; In programming phases, the 4th transistor T4 remains unchanged conducting, thus makes the current potential V of the 3rd node C cmaintain V rEF; In glow phase, the 4th transistor T4 disconnects under the low level control of sweep signal VSCAN, thus makes luminous branch road can conducting, and namely the drive current of luminous branch road can flow through light-emitting component OLED, and then drives light-emitting component OLED luminous.

Due in the non-luminescent stage, i.e. initial phase and programming phases, the equal conducting of the 4th transistor T4, by the current potential V of the 3rd node C cbypass is to reference voltage V rEF.Therefore, do not have extra electric current to flow through light-emitting component OLED, thus ensure that light-emitting component OLED is not luminous in the non-luminescent stage, and then add the contrast of display.In a kind of specific embodiment, reference voltage V rEFshould 0 be less than or equal to, as reference voltage V rEFduring for negative value, | V rEF| larger, more can suppress the brightness irregularities problem that light-emitting component OLED degeneration in time produces.

In another kind of embodiment, the second control signal EN and the first control signal EM also can be identical, and namely the second control signal EN also can be provided by the first control signal EM, and the first control signal EM keeps above-mentioned sequential relationship.Now, at initial phase, because the first control signal EM is high level, therefore, the 6th transistor T6 also conducting, but this does not affect the 4th transistor T4 with reference to voltage V rEFinput to the 3rd node C, i.e. the current potential V of the 3rd node C creference voltage V is remained at initial phase rEF; And identical with the course of work of above-described embodiment with glow phase in programming phases, do not repeat them here.

In another kind of embodiment, as reference voltage V rEFwhen being 0, the second end due to light-emitting component OLED is coupled to the second public electrode VSS, and the current potential of the second public electrode VSS is 0.Therefore, reference voltage V rEFalso can be provided by the current potential of second end of light-emitting component OLED, that is, second pole (such as source electrode) of the 4th transistor T4 is coupled to second end of light-emitting component OLED.In this case, the same said process of the course of work of image element circuit, repeats no more.

Embodiment two:

According to Fig. 3, the second control signal EN is contrary with sweep signal VSCAN phase place, and namely when the second control signal EN is high level, sweep signal VSCAN is low level; When sweep signal VSCAN is high level, the second control signal EN is low level.Based on this point, the present embodiment by changing the type of some transistor, thus reduces the input of signal wire.Please refer to Fig. 4, in the above-described embodiments, each transistor is N channel transistor, and in the present embodiment, 6th transistor T6 is reelected with being P channel type transistor, now, the channel type of the 6th transistor T6 and transistor seconds T2 is different, and the second control signal EN is provided by sweep signal VSCAN.Please refer to Fig. 5, is the signal timing diagram of the present embodiment image element circuit, wherein, and the same embodiment of sequential relationship of sweep signal VSCAN and the first control signal EM, so, in initial phase and programming phases, the 6th transistor T6 conducting; In glow phase, the 6th transistor T6 disconnects.

Those skilled in the art are easy to release the present embodiment according to embodiment one, and to flow through the program current of light-emitting component OLED also identical with formula (2), do not repeat them here.Certainly, when second pole (such as source electrode) of the 4th transistor T4 is coupled to second end of light-emitting component OLED, V in formula cbe 0.

In another embodiment, the 5th transistor T5 also can adopt P channel type transistor, and now, the phase place of the first control signal EM should be contrary with the phase place of the first control signal EM in above-described embodiment, that is, at initial phase, the first control signal EM is low level; In programming phases and glow phase, the first control signal EM is high level.

Embodiment three:

Please refer to Fig. 6, is the image element circuit structure figure of the present embodiment.The present embodiment and above-described embodiment difference are, the position that the light-emitting component OLED of luminous branch road connects is different, and the first end of the light-emitting component OLED of the present embodiment is coupled to the first public electrode VDD, is specially:

The first end (such as anode) of light-emitting component OLED and first pole (such as draining) of the 4th transistor T4 are coupled to the first public electrode VDD; First pole (such as draining) of the 5th transistor T5 is coupled in second end (such as negative electrode) of light-emitting component OLED and second pole (such as source electrode) of the 4th transistor T4; The control pole (such as grid) of the 4th transistor T4 for input and responding scanning signal VSCAN with switched conductive/off-state.Similarly, when light-emitting component OLED is in non-luminescent state, the 4th transistor T4 conducting; Be in luminance at light-emitting component OLED, the 4th transistor T4 disconnects.

Second pole (such as source electrode) of the 6th transistor T6 is coupled to the second public electrode VSS, therefore, in the present embodiment, and the 3rd node C initial potential V cidentical with the current potential of the second public electrode VSS, V in one embodiment c=0.

In the present embodiment, the annexation of other transistor is:

The control pole (such as grid) of third transistor T3 is for inputting sweep signal VSCAN, and the first pole (such as draining) and the second pole (such as source electrode) are coupled respectively to first pole (such as draining) of driving transistors T1 and control pole (such as grid).

The control pole (such as grid) of transistor seconds T2 is for inputting sweep signal VSCAN, and the first pole is coupled to second pole (such as source electrode) of driving transistors T1, and the second pole (such as source electrode) is for input data signal VDATA.

The control pole (such as grid) that the first end of memory capacitance CS is coupled to driving transistors T1 forms Section Point B, and the second pole (such as source electrode) that the second end is coupled to the 6th transistor T6 forms the 3rd node C.

First pole (such as draining) of driving transistors T1 is coupled to second pole (such as source electrode) of the 5th transistor T5, second pole (such as source electrode) is coupled to first pole (such as draining) of the 6th transistor T6, control pole (such as grid) and be coupled to Section Point B, driving transistors T1 provides drive current for light-emitting component OLED under the signal of Section Point B controls.

The control pole (such as grid) of the 5th transistor T5 is for inputting the first control signal EM; The control pole (such as grid) of the 6th transistor T6 is for inputting the second control signal EN.

In the present embodiment, be for all crystals pipe the course of work that N channel transistor sets forth the present embodiment.Image element circuit drives process to be equally also divided into initial phase, programming phases and glow phase, and the signal timing diagram of the present embodiment please refer to and Figure 3 shows that, specifically describes the driving process of the present embodiment below in conjunction with Fig. 6 and Fig. 3.

At initial phase, the first control signal EM is high level, and the second control signal EN is low level, sweep signal VSCAN is high level, therefore, the 6th transistor T6 disconnects, and transistor seconds T2, third transistor T3, the 4th transistor T4 and the 5th transistor T5 all open.In this stage, the current potential of the 3rd node C is identical with the current potential of the second public electrode VSS, is specially V c=0; Section Point B is coupled to the first public electrode VDD by the third transistor T3 of conducting and the 5th transistor T5, and therefore, the current potential of Section Point B is close to the current potential of the first public electrode VDD, and conducting driving transistors T1.

In programming phases, the first control signal EM is low level, and the second control signal EN is low level, and sweep signal VSCAN is high level, and therefore, the 6th transistor T6 disconnects, thus the current potential of the 3rd node C keeps low level current potential, is specially 0.5th transistor T5 disconnects, transistor seconds T2 and third transistor T3 still conducting, and therefore, in this stage, third transistor T3 and driving transistors T1 constitutes the connection of diode form.So Section Point B starts electric discharge, until driving transistors T1 disconnects.When driving transistors T1 disconnects, the current potential of Section Point B is discharged to be stablized to V dATA+ V tH1, wherein, V dATAfor the voltage of the data-signal VDATA that transistor seconds T2 second pole (such as source electrode) inputs, V tH1for the threshold voltage of driving transistors T1.Therefore, at the end of this stage, the voltage difference of memory capacitance CS two ends (Section Point B and the 3rd node C) is V dATA+ V tH1.Memory capacitance CS stores this voltage difference.

In glow phase, the first control signal EM is high level, and the second control signal EN is high level, and sweep signal VSCAN is low level, therefore, and the 5th transistor T5 and the 6th transistor T6 conducting; Transistor seconds T2, third transistor T3 and the 4th transistor T4 disconnect.Now, because Section Point B is in suspended state, therefore, the voltage difference at memory capacitance CS two ends keeps V dATA+ V tH1constant, the drive current flowing through light-emitting component OLED is:

I OLED = β 2 ( V DATA + V TH 1 - V DS 6 - V TH 1 ) 2 - - - ( 3 )

Wherein, V tH1for the threshold voltage of driving transistors T1; V dS6be first pole, pole-the second (such as drain-source) voltage of the 6th transistor T6, have nothing to do with the threshold voltage of driving transistors T1 and the voltage at light-emitting component OLED two ends, α I can be expressed as oLED.So formula can be reduced to:

I OLED = β 2 ( V DATA - V DS 6 ) 2 = β 2 ( V DATA - α I OLED ) 2 - - - ( 4 )

Wherein, β is gain factor, β=μ C oX(W/L) μ and C oXbe respectively carrier mobility and the gate insulation layer electric capacity of driving transistors, W and L represents channel width and the length of driving transistors respectively, and α is and V tH1and V oLEDirrelevant coefficient.As can be seen from the above equation, the drive current I of light-emitting component OLED is flow through oLEDonly with the voltage V of current data signal VDATA dATAand reference voltage V rEFrelevant, with the threshold voltage V of driving transistors T1 tH1and the voltage V at light-emitting component OLED two ends oLEDirrelevant, thus compensate for the change of driving transistors T1 threshold voltage and the brightness irregularities problem of light-emitting component OLED degeneration generation in time.

In addition, due in the non-luminescent stage, i.e. initial phase and programming phases, the equal conducting of the 4th transistor T4, by light-emitting component OLED short circuit.Therefore, do not have extra electric current to flow through light-emitting component OLED, thus ensure that light-emitting component OLED is not luminous in the non-luminescent stage, and then add the contrast of display.

Similarly, in other embodiments, the second control signal EN and the first control signal EM also can be identical, and namely the second control signal EN also can be provided by the first control signal EM, and the first control signal EM keeps above-mentioned sequential relationship.

Similarly, in other embodiments, 6th transistor T6 can also reelect with the transistor for channel type different from other transistor, as in the present embodiment, can reelect with P channel type transistor, now, the channel type of the 6th transistor T6 and transistor seconds T2 is different, and the second control signal EN is provided by sweep signal VSCAN.The signal timing diagram of image element circuit please refer to Fig. 5, wherein, and the same embodiment of sequential relationship of sweep signal VSCAN and the first control signal EM, so, in initial phase and programming phases, the 6th transistor T6 conducting; In glow phase, the 6th transistor T6 disconnects.Those skilled in the art are easy to release the present embodiment according to above-described embodiment, and to flow through the program current of light-emitting component OLED also identical with formula (4), do not repeat them here.

Similarly, in other embodiments, the 5th transistor T5 also can adopt P channel type transistor, now, the phase place of the first control signal EM should be contrary with the phase place of the first control signal EM in above-described embodiment, namely, at initial phase, the first control signal EM is low level; In programming phases and glow phase, the first control signal EM is high level.

Embodiment four:

Be illustrated in figure 7 a kind of display device disclosed in the present application, comprise display panel 100, display panel 100 comprises by multiple two-dimensional pixel with n × m matrix arrangement (i.e. capable m row of n, wherein n and m is positive integer) two-dimensional array that forms, and many controlling grid scan line Gate of the first direction to be connected with each pixel (such as laterally), for providing the sweep signal VSCAN of each image element circuit, with a plurality of data lines Data of second direction (such as longitudinally), for providing the data-signal VDATA of each image element circuit.Same one-row pixels in pel array is all connected to same controlling grid scan line Gate, and the same row pixel in pel array is then connected to same data line Data.The pixel-driving circuit that each pixel of display panel 100 adopts above-described embodiment to provide.Display panel 100 can be display panels, organic electroluminescence display panel, electronic paper display panel etc., and the display device of correspondence can be liquid crystal display, organic light emitting display, electric paper display etc.

Gate driver circuit 200, in gate driver circuit 200, the gated sweep signal output part of gate drive unit circuit is coupled to controlling grid scan line Gate corresponding with it in display panel 100, for generation of the sweep signal VSCAN required for image element circuit, pel array is lined by line scan; Also for providing the first control signal EM and the second control signal EN to each image element circuit line by line.Gate driver circuit 200 can pass through welding and is connected with display panel 100 or is integrated in display panel 100.

Data drive circuit 300, the signal output part of data drive circuit 300 is coupled on data line Data corresponding with it in display panel 100, the voltage data signal V that data drive circuit 300 produces dATAbe transferred in corresponding pixel cell by data line Data to realize gradation of image.Data drive circuit 300 can pass through welding and is connected with display panel 100 or is integrated in display panel 100.

Controller 400, controller 400 is for providing Control timing sequence to gate driver circuit and data drive circuit.

Embodiment five:

The present embodiment also discloses a kind of display circuit driving method, and display circuit adopts the image element circuit of above-described embodiment, and each drive cycle of image element circuit comprises initial phase, programming phases and glow phase, and driving method specifically comprises:

Initial phase, the current potential at third transistor T3 and the 5th transistor T5 conducting initialization memory capacitance CS two ends.

Programming phases, third transistor T3 and transistor seconds T2 conducting, the threshold voltage of data-signal VDATA and driving transistors T1 is inputed to the first end of memory capacitance CS by transistor seconds T2 by transistor seconds T2 and third transistor T3, and is stored in this node by memory capacitance CS.

Glow phase, driving transistors T1 produces drive current according to the pressure differential at memory capacitance CS two ends, and drives light-emitting component OLED luminous.

Above content is in conjunction with concrete embodiment further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, some simple deduction or replace can also be made.

Claims (10)

1. an image element circuit, is characterized in that, comprising:
Memory capacitance (CS), third transistor (T3), transistor seconds (T2) and for being coupling in the luminous branch road between the first public electrode (VDD) and the second public electrode (VSS);
Luminous branch road comprises the 5th transistor (T5), driving transistors (T1), the 6th transistor (T6) and the light-emitting component of series connection; Wherein, the 5th transistor (T5) is connected between the first public electrode (VDD) and driving transistors (T1), and the 6th transistor (T6) is connected between the second public electrode (VSS) and driving transistors (T1); The control pole of the 5th transistor (T5) is for inputting the first control signal (EM); The control pole of the 6th transistor (T6) is for inputting the second control signal (EN); First pole of driving transistors (T1) is coupled to the second pole of the 5th transistor (T5), and the second pole is coupled to the first pole of the 6th transistor (T6), controls pole and is coupled to Section Point (B);
The control pole of third transistor (T3) is for inputting sweep signal (VSCAN), and the first pole and the second pole are coupled respectively to the first pole and the Section Point (B) of driving transistors (T1);
The control pole of transistor seconds (T2) is for inputting sweep signal (VSCAN), and the first pole is coupled to the second pole of driving transistors (T1), and the second pole is used for input data signal (VDATA);
The first end of memory capacitance (CS) is coupled to Section Point (B), and the second end is coupled to the second pole of the 6th transistor (T6);
In programming phases, 5th transistor (T5) and the 6th transistor (T6) respond the first control signal (EM) and the second control signal (EN) respectively and disconnect, and the threshold voltage of data-signal (VDATA) and driving transistors (T1) is stored in Section Point (B) by transistor seconds (T2) and signal (VSCAN) conducting of third transistor (T3) responding scanning;
In glow phase, transistor seconds (T2) and third transistor (T3) respond input sweep signal (VSCAN) respectively and disconnect, 5th transistor (T5) and the 6th transistor (T6) respond the first control signal (EM) and the second control signal (EN) and conducting respectively, and driving transistors (T1) conducting under the control of Electric potentials of Section Point (B) provides drive current for light-emitting component.
2. image element circuit as claimed in claim 1, it is characterized in that, the first pole of described 5th transistor (T5) is used for being coupled to the first public electrode (VDD); The first end of described light-emitting component is coupled to the second pole of the 6th transistor (T6), and the second end is used for being coupled to the second public electrode (VSS).
3. image element circuit as claimed in claim 1, it is characterized in that, the first pole of described 5th transistor (T5) is coupled to the second end of described light-emitting component; The first end of described light-emitting component is used for being coupled to the first public electrode (VDD); Second pole of described 6th transistor (T6) is used for being coupled to the second public electrode (VSS).
4. image element circuit as claimed in claim 2, is characterized in that, also comprise the 4th transistor (T4);
First pole of described 4th transistor (T4) is coupled to the first end of described light-emitting component, and the second pole is used for input reference voltage (V rEF), control pole for inputting sweep signal (VSCAN); When light-emitting component is in non-luminescent state, described 4th transistor (T4) conducting, when light-emitting component is in luminance, described 4th transistor (T4) disconnects.
5. image element circuit as claimed in claim 4, is characterized in that, described reference voltage (V rEF) be less than or equal to 0.
6. image element circuit as claimed in claim 4, it is characterized in that, the second pole of described 4th transistor (T4) is coupled to the second end of described light-emitting component, described reference voltage (V rEF) provided by the current potential of the second end of described light-emitting component.
7. image element circuit as claimed in claim 3, is characterized in that, also comprise the 4th transistor (T4);
First pole of described 4th transistor (T4) is coupled to the first end of described light-emitting component, and the second pole is coupled to the second end of described light-emitting component, controls pole for inputting sweep signal (VSCAN); When light-emitting component is in non-luminescent state, described 4th transistor (T4) conducting, is in luminance at light-emitting component, and described 4th transistor (T4) disconnects.
8. the image element circuit as described in claim 1-6 any one, is characterized in that, described 6th transistor (T6) is identical with the channel type of described 5th transistor (T5), and described second control signal (EN) is identical with described first control signal (EM); And/or;
The channel type of described 6th transistor (T6) and described transistor seconds (T2) is different, and described second control signal (EN) and described sweep signal (VSCAN) are provided by common signal.
9. a display device, is characterized in that, comprising:
Image element circuit matrix, described image element circuit matrix comprises the image element circuit as described in claim 1-8 any one being arranged in the capable m column matrix of n, described n and m be greater than 0 integer;
Gate driver circuit, for generation of scanning pulse signal, and provides sweep signal by each horizontal scanning line formed along first direction to image element circuit; Also for providing the first control signal and the second control signal along first direction to each row image element circuit;
Data drive circuit, for generation of the data voltage signal representing half-tone information, and provides data voltage signal by each data line formed along second direction to image element circuit;
Controller, for providing Control timing sequence to gate driver circuit and data drive circuit.
10. a driving method for the image element circuit as described in any one of claim 1-8, is characterized in that, each drive cycle of described image element circuit comprises initial phase, programming phases and glow phase, and described driving method comprises:
At described initial phase, the current potential at described third transistor (T3) and described 5th transistor (T5) conducting initialization memory capacitance (CS) two ends;
In described programming phases, described third transistor (T3) and described transistor seconds (T2) conducting, the threshold voltage of data-signal (VDATA) and driving transistors (T1) inputs to the first end of memory capacitance (CS) by transistor seconds (T2) and third transistor (T3), and is stored in this end by memory capacitance (CS);
In glow phase, described driving transistors (T1) produces drive current according to the pressure differential at described memory capacitance (CS) two ends, and drives light-emitting component OLED luminous.
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